U.S. patent number 4,079,359 [Application Number 05/628,293] was granted by the patent office on 1978-03-14 for compact transfer replicate switch for magnetic single wall domain propagation circuits and method of making same.
This patent grant is currently assigned to Rockwell International Corporation. Invention is credited to Isoris S. Gergis.
United States Patent |
4,079,359 |
Gergis |
March 14, 1978 |
Compact transfer replicate switch for magnetic single wall domain
propagation circuits and method of making same
Abstract
A single-level process in which a precision registration process
step is replaced by a gross alignment process step in delineation
of magnetic and non-magnetic levels in magnetic bubble domain
devices. In the instant process, one fine definition and two gross
definition process steps are used to define the propagation
structure and the fine control conductors simultaneously. This
process permits certain fabrication advantages and improved device
operation. A compact transfer/replicate switch is fabricated by the
new process. This switch permits the transfer of magnetic bubbles
between more compactly arranged propagation paths, such as storage
tracks and access tracks, in magnetic bubble domain devices and
systems.
Inventors: |
Gergis; Isoris S. (Placentia,
CA) |
Assignee: |
Rockwell International
Corporation (El Segundo, CA)
|
Family
ID: |
24518280 |
Appl.
No.: |
05/628,293 |
Filed: |
November 3, 1975 |
Current U.S.
Class: |
365/43; 216/13;
216/22; 216/47; 365/12; 365/39; 427/128 |
Current CPC
Class: |
G11C
19/0858 (20130101); G11C 19/0883 (20130101); H01F
41/34 (20130101) |
Current International
Class: |
H01F
41/00 (20060101); H01F 41/34 (20060101); G11C
19/00 (20060101); G11C 19/08 (20060101); G11C
019/08 (); B32B 031/00 () |
Field of
Search: |
;340/174TF ;156/659
;29/604 ;427/128,130 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
IEEE Transactions on Magnetics, vol. Mag. 9, No. 3, Sept. 1973, pp.
474-480..
|
Primary Examiner: Moffitt; James W.
Attorney, Agent or Firm: Hamann; H. Fredrick Weber, Jr.; G.
Donald
Claims
Having thus described a preferred embodiment of the invention, what
is claimed is:
1. A method of making a magnetic bubble domain device by
providing a magnetic film capable of supporting magnetic bubble
domains in the presence of properly applied magnetic fields,
forming a layer of dielectric material on at least one surface of
said magnetic film,
forming a layer of electrically conductive material on said layer
of dielectric material,
applying a first gross definition mask to said layer of
electrically conductive material,
removing portions of said layer of electrically conductive material
to expose portions of said layer of dielectric material,
forming a layer of selectively magnetizable material on said layer
of electrically conductive material and the exposed portions of
said layer of dielectric material,
applying a fine definition mask to portions of said layer of
magnetizable material,
removing portions of said magnetizable material in accordance with
said fine definition mask,
applying a second gross definition mask to said layer of
magnetizable material, and
removing additional portions of said layer of magnetizable material
in accordance with said second gross definition mask.
2. The method recited in claim 1 including
applying a second fine definition mask to said layer of
magnetizable material and exposed portions of said layer of
electrically conductive material, and
removing selected portions of said layer of magnetizable material
and said layer of electrically conductive material in accordance
with said second fine definition mask.
3. The method recited in claim 2 wherein said magnetic film
comprises
a magnetic garnet material,
said layer of electrically conductive material comprises a metal
such as aluminum, copper or alloys thereof,
said magnetizable layer comprises permalloy, and
said masks comprise photoresist materials.
4. A magnetic bubble domain device comprising a layer of magnetic
bubble domain material and a layer of magnetizable material
wherein:
said layer of magnetizable material is formed to comprise;
at least two columns of chevron shaped elements having the apices
of each column substantially colinear and pointing toward each
other,
at least one propagation path element adjacent one of said columns
of chevron shaped elements,
a first bar element substantially parallel to a line defined by the
apices of the chevron-shaped elements of said columns and adjacent
to but spaced from the ends of said one of said columns of chevron
shaped elements,
a second bar element substantially perpendicular to said first bar
element and extending away from said one column, and
a third bar element interposed between and angularly disposed
relative to each of said first and second bar elements; and,
each of said first, second and third bar elements having an end
thereof arranged colinearly with each other and in line with said
one propagation path element.
5. The device recited in claim 4 including a second propagation
path element adjacent the other of said columns of chevron shaped
elements wherein said one propagation path element and said second
propagation path element form portions of separate propagation
paths.
6. The device recited in claim 4 including:
a central bar element formed from said layer of magnetizable
material,
said central bar element connected to all of the chevron shaped
elements in each of said columns of chevron shaped elements.
7. The device recited in claim 6 wherein:
said central bar element is substantially parallel to the ends of
said chevron shaped elements and said first bar element.
8. The device recited in claim 4 including:
conductor means disposed under said layer of magnetizable material
and arranged to alter the magnetic field in said device in response
to a control signal.
9. The device recited in claim 8 including:
a dielectric layer disposed between said layer of magnetizable
material and said layer of magnetic bubble domain material such
that said conductor means is electrically isolated from one of said
layer of magnetizable material and said layer of magnetic bubble
domain material.
10. The device recited in claim 5 wherein:
said one propagation path element is comprised of chevron shaped
elements, and;
said second propagation path element is comprised of elements
having substantially rectilinear configurations such as H-bars,
T-bars or I-bars.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a process for making field accessed
bubble domain devices and to a device which permits manipulation,
e.g. transfer or replication, of magnetic bubble domains between
different propagation paths in typical magnetic bubble domain chip
organization.
2. Description of Prior Art
In fabricating bubble domain devices, many processes are known.
Frequently used processes are the so-called "two-level" or
"one-level" processes. It is desirable to use as few "levels" of
processing as possible in order to reduce fabrication complexity
and to improve yields. Thus, the one-level process is frequently
used in order to produce devices in which the permalloy overlay
circuit serves as both the source of the bubble drive field and as
a conductor of control currents for functions such as generation,
annihilation, switching and the like. However, such devices suffer
from certain drawbacks. For example, permalloy has a high
resistivity (relative to the conductor material) wherein narrow
control conductors can cause overheating and device burnout. Also,
return current leads frequently interfere with bubble domain
propagation in other components. Moreover, non-magnetic return
current leads are sometimes necessary (or desirable) for proper
operation of devices or systems. Consequently, a one-level process
which overcomes these problems, and devices fabricated by such a
process are desirable.
Devices or systems that utilize magnetic bubbles for storage of
data in a binary form typically use soft magnetic overlay
structures for propagation and storage of bubbles. These structures
are usually arranged in arrays of T-I, X-T or chevron patterns.
Transferring and replication (by stretching and separation of
bubbles) between different tracks is accomplished by selectively
interconnecting these tracks. Current carrying conductors are used
to effect the transfer or the replicate functions in non-passive
switches. Examples of these gates or switches are the so-called
dollar sign transfer gate and the chevron-chevron
transfer-replicate switch.
The dollar sign transfer gate disclosed in U.S. Pat. No. 3,714,639
to Kish et al., selectively diverts bubbles from T-I storage tracks
and T-I access tracks when a current pulse is applied to the
conductor. The dollar sign transfer gate is fabricated using a two
step process in which the conductor level must be processed before
the permalloy layer. These layers must be aligned to each other
with a high degree of accuracy.
The chevron-chevron transfer replicate switch as described by T. J.
Nelson, AIP Conference Proceedings, No. 18, Part 1, pp. 95-99
(1974) is used to transfer bubbles from one chevron path to
another, such as between major and minor loops. This switch can be
fabricated using a single level definition. One fine-definition
process is needed to define both the permalloy and the conductor
patterns. Chevron tracks, however, are not as compact as the T-I or
T-X tracks such that fewer bubbles are stored for the same device
surface area. Consequently, the device described by Nelson requires
extensive chip geometry utilization and relatively high time
requirements for data (bubble domain) throughput.
SUMMARY OF THE INVENTION
This invention relates to a process for making bubble domain
devices such as a transfer/replicate switch device fabricated from
soft magnetic material such as permalloy which is used in the
manipulation of magnetic single wall domains (bubbles) between
propagation tracks or paths in bubble domain devices or systems.
The switch device is of the chevron-chevron type which includes a
current conductor formed with portions (e.g. chevron columns) of
separate propagation paths and properly aligned structures for
controlling the propagation of bubble domains in a minimum chip
area.
BRIEF DESCRIPTION OF DRAWING
FIG. 1 is a cross sectional view of a portion of a composite
fabricated in accordance with the invention.
FIGS. 2 and 3 are cross sectional views of the composite shown in
FIG. 1 after further operations.
FIG. 4 is a perspctive of a device fabricated in accordance with
the invention.
FIG. 5 is a plan view of a device fabricated in accordance with the
instant invention.
Referring now to FIG. 1, there is shown a cross-section of a
portion of a composite fabricated in accordance with the instant
invention. Initially, a suitable substrate 10 is provided. In a
preferred embodiment, this substrate may be of the so-called
gadolinium gallium garnet (G.sup.3) type of material. A film or
layer 11 of magnetic material is provided on a surface of substrate
10. Film or layer 11 may typically be a magnetic garnet film.
However, any suitable material for supporting magnetic bubble
domains is contemplated. Typical compositions for substrate 10 and
layer 11 are well known in the art.
A layer 12 of a suitable electrically insulating material such as
silicon dioxide is formed on the surface of magnetic film 11. A
layer 13 of conductive material such as but not limited to
aluminum, copper alloy is formed on the surface of the dielectric
12.
It should be noted that any suitable process for forming the
various layers is contemplated. That is, a chemical vapor
deposition (CVD) process may be used, sputtering may be used or a
liquid phase epitaxy (LPE) technique may be used. The particular
process to be utilized is a function of the materials and the
composite to be formed thereby and is not limitative of the
invention.
Once the various processes have been decided upon and the
appropriate composite produced, as described above, a basis for a
magnetic bubble domain device, such as a memory or other system, is
provided.
Initially, a suitable mask (not shown) is placed on the surface of
the conductive layer 13 of the composite shown in FIG. 1. Any
suitable type of mask such as a photoresist or the like may be
utilized. Once the mask has been appropriately applied and formed,
a suitable etching process such as a chemical etching, ion milling
or the like, is performed. This masking and etching process is the
relatively gross alignment process which is used in areas where
fine line definition is not required. The etching process permits
the removal of relatively large areas of the conductive layer at
the surface of the composite. Thus, relatively large portions such
as portion 13A (indicated by dashed outline) of layer 13 can be
removed. Typically, these relatively gross alignment areas are
established in those areas where careful alignment of structures is
not required. For example, in those areas where a detector
structure is to be inserted, a relatively large conductor may be
used which does not require critical alignment of the
structure.
Referring now to FIG. 2, the composite shown in FIG. 1 is now
provided with a layer 14 of a suitable magnetizable material such
as, but not limited to, permalloy. The permalloy layer is deposited
in a preferred manner over the surface of layer 13 of the
composite. An additional masking layer 15 such as photoresist or
the like is then deposited over the surface of magnetizable layer
14. Mask 15 is defined in a suitable manner such as by exposure and
development wherein the preferred pattern in the magnetizable area
14 is defined. The appropriate etching process is performed on the
composite wherein the unmasked portions of layer 14 are removed as
shown in FIG. 2. It should be noted that mask 15 provides a
fine-line definition of the pattern desired in layer 14. This
operation is performed to define the propagation pattern and the
fine-line control conductor. It must be understood that regardless
of the etching process (whether chemical etch, ion milling or the
like) this step should be closely controlled to avoid the removal
of any appreciable amount of conductor layer 13. That is, only the
permalloy pattern should be effected at this point.
A further gross mask (not shown) is aplied to the entire surface of
the composite shown in FIG. 2 including the photoresist masks which
are left on the unetched permalloy. This second gross mask is,
typically, used to define the return current leads. When the second
gross mask has been appropriately provided and developed in a
suitable manner, the etching of conductor layer 13 can be performed
using ion milling, a chemical etchant or the like. The type of
etching is, to some extent, dependent upon the material of the
conductor and the types of masking material or vice versa.
Reference is made to FIG. 3 which shows the cross-sectional view of
the device after the second gross masking and etching operation is
completed. In addition, the photoresists (and other masking
materials) have been removed. In addition, portions 13B and the
like are removed from conductor layer 13. Of course, other portions
13C (and the like) are not removed inasmuch as they were masked by
the second gross mask. This permits individual control conductors
to be provided for the system.
Of course, it should be understood that it may be desirable in some
instances to use a second fine-line definition process for defining
and producing the control conductors. This second fine-line
definition process may be used in addition to the fine-line
definition process used in establishing the propagation structure.
The second process has the advantage of establishing the permalloy
or magnetizable layer 13 in a strictly planar form wherein no step
coverage by the conductor layer is required. For example, the step
portions 31 and 32 of layer 14 can be eliminated by the second
fine-line definition process. Avoiding step coverage avoids the
difficulty of establishing permalloy patterns or elements over the
edges of the conductor inasmuch as the conductor layer extends
everywhere except in the detector area.
Referring now to FIG. 4, there is shown a portion of a
transfer/replicate switch fabricated in accordance with the process
described supra. Thus, the layer portions 14 represent the portions
of the magnetizable layer which are retained during the fine-line
process. The conductor portions 13 immediately beneath the
magnetizable layers 14 are also defined during the fine line
definition. However, it can be seen that portion 100 of layer 13 is
a portion of a return current lead which has little or no
requirement for careful definition. Consequently, portion 100 of
layer 13 is determined by utilization of the second gross masking
process.
As is seen, conductor portion 100 of layer 13 is relatively large
compared to the conductor portion 13 under the associated portions
of magnetizable layer 14. Because of the relative sizes, the
alignment of conductor portion 100 is not critical relative to the
permalloy portions or magnetizable layer 14. In other words, if
conductor portion 100 were to be out of alignment by half a line
width (or perhaps more), an interconnection between conductor
portion 100 and conductor portion 13 is still effected readily.
However, if a fine-line masking arrangement were utilized to define
the control conductor 14, it is possible that a misalignment of
half a line width would be extremely detrimental and, perhaps,
catastrophic to the operation of the device.
Referring now to FIG. 5, there is shown one embodiment of a
transfer/replicate switch fabricated in accordance with the method
described above. Again, magnetizable layer 11 is covered by a
dielectric layer 12. The conductive layer 13 (FIGS. 1-4) is etched
wherein conductor portions 100 and 101 are defined by the gross
definition process and the other elements of magnetizable layer 14
(see FIGS. 1-4) and the attendant conductor layer are defined by
the fine-line definition process.
The transfer/replicate switch 500 comprises primarily a pair of
opposite chevron columns 502 and 503. In the embodiment described,
the chevron columns include three chevrons each. However, the
number of chevrons is not limitative of the invention.
Chevron columns 502 and 503 are oppositely directed. That is, the
apices of the chevrons of the columns point toward each other
wherein columns 502 and 503 are essentially anti-parallel. The
apices of each of the chevrons in columns 502 and 503 are connected
together by magnetizable layer strip 501. Typically, the chevrons
and strip 501 may be fabricated of permalloy or the like. It must
be understood that a conductor portion extends under strip 501 and
interconnects with conductor portions 100 (see FIG. 4).
In addition, elements 506, 507 and 508 as well as elements 504, and
510 are included in the transfer/replicate switch. Each of the
aforementioned elements are in the form of an I-bar element. These
bars are arranged as a transition type array. In particular,
elements 504 and 506 are essentially parallel to each other and
parallel to the ends of chevron column 503. Elements 508 and 510
are arranged substantially perpendicular to elements 506 and 504,
respectively. In addition, element 507 is arranged at an angle to
each of elements 508 and 506. One end of element 507 is interjected
between the adjacent ends of elements 506 and 508. It should be
noted that adjacent ends of elements 506, 507 and 508 are aligned
in a virtually linear arrangement which is substantially co-linear
with element 506. Likewise, the adjacent end of element 510 is
located substantially co-linearly with element 504. In addition,
the co-linear arrangements of elements 506, 507 and 508 are aligned
with one bar portion of element 511 which is an H-shaped element.
The other side of H-shaped element 511 is substantially co-linear
with the adjacent ends of elements 504 and 510. As noted, element
511 is one element of a propagation path wherein bubbles enter and
exit switch 500 in accordance with the arrows shown adjacent to
element 511.
Elements 506B, 507B and 511B are counterparts to elements 506, 507
and 511, respectively. These counterparts are contained in
additional switches, propagation paths or the like which are
similar to the element 511 shown and described. Likewise, elements
504A and 511A correspond to elements 504 and 511, respectively, in
additional device structures.
Chevron columns 512 and 513 are additional columns of chevrons
which are disposed adjacent to chevron column 502. Columns 512 and
513 may represent additional columns of chevrons which form a
portion of a propagation path, a detector or the like.
In operation, it should be considered that suitable propagation
paths comprising T-bars, I-bars and/or H-bars (or combinations
thereof) are formed in appropriate fashion such as storage loops or
the like. These loops include elements 511, 511A and 511B
respectively. It is conceivable that each of these elements may be
portions of a single propagation path. However, it is also
conceivable that each of these elements may represent a portion of
an individual circuit path or loop. For example, a plurality of
"minor loops" may respectively include one of these elements.
Regardless of the arrangements of the various minor loops, the
description relates only to the individual transfer/replicate
switch 500 as shown in FIG. 5. Thus, bubble domains may be
propagated through the propagation path and enter the switch as
suggested by the arrow at the lower right portion of the switch.
The bubbles propagate under the influence of the fields H.sub.B and
H.sub.R in a well known fashion.
As the field H.sub.R rotates in a counterclockwise direction, a
bubble domain is transferred from element 511 to the left end of
element 508. The bubble then continues to be transferred to the
respective ends of elements 507 and 506 at which magnetic poles are
formed by the rotating field. The bubble, in response to field
H.sub.R, is then transferred to the right ends of the chevrons in
columns 503 where the bubble domain is stretched along the chevron
column as is known in the art.
In the normal operation of the device, a bubble moves from the
right ends of chevrons of column 503 to the apices thereof through
to the left ends of these chevrons until it is transferred to the
end of element 504. From element 504 the bubble domain is
transferred to element 510 and then to element 511 and element 510B
of the propagation path as suggested by the arrow.
In the replicate-out mode of operation (i.e. a bubble in the
propagation path is replicated into the access path), a bubble is
transferred through elements 511, 508, 507 and 506 as noted supra.
In addition, the bubble is transferred to the right ends of the
chevrons of column 503 in the usual manner. Thus, the bubble is
stretched along the length of the chevron column 503. In response
to the field H.sub.R, the stretched bubble tends to move toward and
slightly beyond the apices of the chevrons of column 503. When the
bubble is just past the apices of the chevrons in column 503, a
current is supplied to conductor 100 which current also passes
through the conductor under element 501. This current is of
sufficient intensity and proper polarity to produce a magnetic
field which is effective to stretch the bubble across the space
between chevron columns 502 and 503. Thus, an elongated bubble
domain is essentially stretched across columns 502 and 503 slightly
to the left of the apices and element 501. The current is not of
sufficient intensity, polarity or duration to block the movement of
the bubble domain nor to overcome the effect of the rotating field.
However, the stretched bubble is retained briefly on the output
side of element 501 due to the field produced by the current in the
conductor therebeneath. As the field continues to rotate the
opposite ends of the bubble tend to move in opposite directions
along the chevrons in columns 502 and 503. In particular, the lower
portion of the bubble tends to move toward the left end of chevrons
in column 503 while the upper bubble portion remains adjacent the
apices of the chevrons in column 502. As the bubble stretches
between the chevron columns and across element 501, a current pulse
of opposite polarity (relative to the stretch current) and of
appropriate intensity is applied via conductors 100 to the
conductor under element 501. This current produces a magnetic field
of appropriate intensity and polarity adjacent element 501 to cause
the bubble to be severed into two separate bubbles at the
respective chevron columns 502 and 503. The one bubble then
continues, as described supra, through the propagation path as
determined by elements 504, 510, 511 and so forth. The other
bubble, under the influence of rotating field H.sub.R propagates
toward the right ends of the chevrons in column 502 and, thence, to
the chevrons in column 513 and so forth.
Thus, a bubble in the propagation path suggested by H-bar 511
traverses switch 500 and is returned to the bubble path or storage
loop. In addition, the bubble is replicated into the access path of
the upper chevrons where it may be supplied to a detector, a major
loop or the like. It is important to note that the bubble
propagation and replication has taken place within one period of
the rotating field H.sub.R as well as within one element space of
the magnetic bubble domain system. This operation permits
substantial packing density of devices and, thus, information, as
well as high throughput of information.
In the replicate-in mode informaion is transferred from the access
path represented by the chevron columns at the upper portion of the
figure (e.g. chevron columns 512 and 513) into the storage loop
(e.g. represented by element 511). Initially, a bubble is
propagated along the access path under the influence of rotating
field H.sub.R in the usual manner. Thus, a bubble is propagated
from the chevron column 512 into chevron column 502 in a typical
fashion. As the field continues to rotate, the bubble propagates
toward and slightly beyond, i.e. on the output side of, the apices
of the chevrons in column 502. At that time, a current is supplied
via conductors 100 to the conductor under element 501. This current
is of proper polarity and sufficient intensity to effectively
retain the bubble adjacent the apices of the chevrons of column
502. Moreover, the applied current provides a magnetic field which
causes the bubble to stretch to the apices of the chevrons in
column 503 wherein the bubble encompasses both chevron columns. The
current is removed when the bubble has stretched between the right
ends of chevron column 502 and the left end of column 503 in
response to the rotating field H.sub.R. The bubble stretches across
element 501. A cutting current pulse is applied via the conductor
under element 501 wherein two separate bubbles propagate through
the respective paths as discussed supra.
In the transfer modes of operation (transfer-in or transfer-out)
operation of the circuit is substantially similar to that described
above. However, in the transfer modes the bubble is transferred
from one propagation path to the other without continuing along the
original path. Thus, there is no replication of bubbles.
In the transfer-in mode, a bubble propagates through the
propagation path, for example, from element 511 to elements 508,
507 and 506 to the right end of chevron 503, respectively. As the
bubble is propagated toward the apices of the chevrons of column
503, a current is supplied via conductors 100 to the conductor
beneath element 501. This current is of the proper polarity and
sufficient intensity to effectively block the passage of the bubble
when it reaches element 501. The current is maintained until the
rotating field H.sub.R is substantially reversed wherein the
magnetization of the column 502 is magnetically attractive. It
should be noted that element 501 and the magnetic field produced by
the conductor under element 501 prevents the bubble in the chevron
503 from being annihilated even as the chevron column 503 becomes
magnetically repulsive in response to field H.sub.R.
When chevron column 502 is magnetically attractive, the bubble on
column 503 is attracted to column 502. When the bubble is attracted
to column 502, the rotating field H.sub.R continues to operate and
to propagate this bubble through the access path in a normal
fashion. It is noted that the field supplied by the current in the
conductor under element 501 has blocked the passage of a bubble
through to the left side of chevron column 503 wherein a bubble is
transferred but not replicated.
Likewise, in a transfer-in operation, a bubble is propagated to the
left end of chevron column 502. When the bubble propagates toward
the apices of the chevrons in column 502, the magnetic field is
produced by passing a current through the conductor under element
501. This field blocks passage of the bubble in chevron column 502.
Upon rotation of field H.sub.R, chevron column 503 becomes
magnetically attractive, attracts the bubble from chevron column
502 and propagates the bubble through the associated path
comprising elements 504, 510, 511 and so forth.
Some features and designs of switch 500 are described in the
aforementioned paper of T. J. Nelson. However, it is noted that in
switch 500 of the instant invention, element 506 is disposed
substantially parallel to the ends of the respective chevrons of
column 503. In addition, element 508 is disposed substantially
perpendicular to element 506. Element 507 is disposed intermediate
to elements 506 and 508 at a preferred angle which may be
determined as a function of the angle described by respective arms
of chevrons in the respective chevron columns. Importantly though,
it should be noted that the adjacent ends of elements 506, 507 and
508 are substantially co-linear with each other and with element
511 of the propagation paths. Likewise, output elements 504 and 510
have ends thereof which are substantially colinear with the other
side of propagation path element 511.
Element 550, shown in dashed outline, may be included in either the
input or output configuration. That is, an element such as element
550 may be included in the output portion of switch 500. As an
alternative arrangement, in order to provide greater design freedom
or modularity, an element such as 550 may be included along with
element 509 as well as element 507 wherein essentially an X-shaped
element is provided. Utilizing such an X-shaped element (elements
550 and 509 for example) permits closer control of both the input
and output paths for the bubble. However, such an X-shaped
configuration element is not essential to the operation of switch
500.
Thus, there has been described the process for forming magnetic
devices and, in particular, a switch which can be used for
replication or transfer of magnetic bubbles from or between
propagation paths in a bubble domain system. It is clear that
modifications may be made to either the process or the device
described herein. However, any modification which falls within the
purview of this description is intended to be included herein as
well. The described embodiments are intended to be illustrative
only and not to be limitative. The limitations of the invention are
determined by the scope of the claims appended hereto.
* * * * *